Telephone-receiver diaphragm



Aug. 4 1925 1,548,106

- J. B. SPEED ET AL.

TELEPHONE RECEIVER DIAPHRAGM Filed July 2, 1925 Wye/fora: I Mamas 5. Speed 4 rf/wr fi/A.

JAMES IBUCHNER SPEED, 01? NEE? YORK, AND ARTHUR H. FALILOF BROOKLYN, NEW.

YORK, ASSIGNOPIS T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YURK, N. Y.,' A CQRPO'IIUN 0' NEW YURK.

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Application filed July 2, 1923. Serial No. 648,884.

To allwhom it may concern; Be it known that we, Jmuns B. SPEED and ARTH R H. FALK, citizens of the United States, residing at New York, in the county of .New York, State of New York, I and Brookl n, in the county 01 Kings, State of New ork, respectively, have invented certain new and useful Improvements in Telc-.

phone-Receiver Diaphragms, of which the following is a full, clear, concise, and exact description. y

This invention relates' to methods of stretching diaphragms and its object is to provide an acoustic diaphragm having a highnatural period of vibration.

In accordance with the features of this invention a diaphragm to be stretched is fastened near its outer edge to a relatively expansible' conical ring, and this ring is stretched uniformly to a slightly larger diameter by forcing into it a second conical ring having an outerdiameter slightly larger than thesmallest inner diameter of the first ring, and composed preferably of somewhat heavier and less yielding material.

In its application to the manufacture of acoustic apparatus for telephonic or similar purposes utilizing metallic diaphragms, the diaphragm is fastened to the relatively expansible metallic ring by soldering, brazing welding, or staking and this ring is uniformly stretched to'give-the desired tension to the'diaphragmnb'y-iircin into it a second ring, thus stretching the iaphragm radially, and uniformly' By the use of this invention-diaphragms are prqvided which have not only an unusually high period of natural vibration, but a uniform radial stress throughout by reason of the flow and adjustment of the metal of the diaphragm at its yield point. It makes possible the use 1 of an exceedingly thin diaphragm which maybe held taut without making the edge portions thicker than the middle portion and without de forming the edge portion by corrugating or punching. This feature enables the use, if desired, of a stretched diaphragm of very brittle aterial such as high silicon steel, which vi ill .introduce a high electrical resistance for the purpose of diminishing eddy currents. which is in all respects superior. to those diaphragms stretched ln-itl16 usual manner.

In short, a diaphragm is obtained A feature of the invention is the provision of an improved mounting whereby the diaphragm is tensioned and positively held in its adjusted vibrating periods through the provision of a plurality of rings adapted to form with the diaphragm a unitary struc: ture which may be inserted or removed from the instrument with which it is used without changing thev adjustment of the diaphragm.

The drawings show one embodiment of the invention. Fig. 1 shows a diaphragm and the apparatus for stretching the same.

Fig. 2 shows the apparatus when the diaphragm is stretched. Fig. 3 shows this apparatus embodied in a telephone receiver,

A ring 6, preferably conical in shape, has fastened to its smaller end a diaphragm 7, which may be composed of metal or other material. The ring 6, which should be of expansible material, is secured to the diaphragm by any satisfactory method; for example, by soldering, brazing, staking, or

welding. A'second ring 8 conical in shape, has an outer diameter at its smaller end somewhat reater than the inside diameter of ring 6 w ere it touches the diaphragm 7. Ring 8-is pressed into ring 6 toward the diaphragm to force ring 6 outwardly in all directions. Ring 6 carries outwardly with it those portions of the diaphragm to which it is attached, thus uniformly stretching the diaphragnn For-this purpose a press which exerts an equal pressure on all sides of ring 8 should he used, in order to secure the desirable uniform stress throughout the diaphragm. Ring 8 should referably be made of heavier or less yiel 'ngmaterial than ring 6. For example, ring 6 may be composed of thin, soft iron or steel having a low yield point, and ring 8 may be composed of thicker or harder iron or steel.

.When it is desired to solder the diaphragm to the ring Gin cases where the diaphragm is composed of a metal or alloy which is noteasily or strongly solderable, a rim of tin or other metal I may be electroplated upon the outeredge of the diaphragm by suitably rotating its rim inan electrolytic bath so as to deposit thereon a thin coating of metal to which the ring may be soldered. While the stretched diaphragm has propentice which make it especially desirable for use in acoustic apparatus for telephonic or like purposes such as the telephone receiver shown in Fig. 3, it may be used for any purpose for which a stretched diaphragm is required.

What is claimed is:

1. In combination, a ring, a diaphragm secured to one edge thereof and an expanding member forced into said ring for stretching the diaphragm uniformly and to form with the said ring a unitary structure for permanently holding said diaphragm stretched.

2. In combination, a ring, a diaphragm secured to one edge thereof, a second heavier ring having its outside diameter greater than the inside diameter of the first ring and forced into said first ring for stretching the diaphragm uniformly and to form with the first ring a unitary structure for nently holding said diaphragm stretc 18d.

erma- In Witness whereof, we hereunto subscribe 20 our names this 27th day of June A. D.,1923.

JAMES BUCHNER SPEED ARTHUR H. FALK. 

